A Spanish court has charged a train driver with multiple cases of negligent homicide following an accident that killed 79 people, a court statement said.

Francisco Jose Garzon, the train driver, was charged on Sunday but released on bail after being questioned by an investigative magistrate.

The statement said Garzon must appear in court once a week and is forbidden to leave Spain without permission.

Garzon was driving the train carrying 218 passenger in eight cars that hurtled far over the 80kph speed limit into a high-risk curve on Wednesday evening. The train tumbled off the tracks and slammed into a concrete wall, with some of the cars catching fire.

The Spanish rail agency has said the brakes should have been applied four kilometres before the train hit the curve.

A local resident who rushed to the scene of the accident said in an interview broadcast on Sunday that minutes after the crash, Garzon had told him that he had been going fast and could not brake in time.

Evaristo Iglesias said he and another person accompanied the blood-soaked Garzon to flat ground, where other injured people were being laid out, waiting for emergency services to arrive.

Juan Jesus Garcia Fraile, the secretary-general of Spain's train drivers' union, told public radio that the track was not equipped with braking technology to slow the train down automatically if the driver failed to do so when required.

Freed on bail

Garzon was not sent to jail or required to post bail because none of the parties involved felt there was a risk of him fleeing or attempting to destroy evidence, the statement said.

The train driver's license had been withdrawn.

Iglesias was among the survivors and witnesses who began to give evidence to police on Sunday.

On Sunday, the death toll from the train derailment rose to 79 when an injured passenger died at University Hospital in Santiago de Compostela, officials said.

She was identified as American Myrta Fariza of Houston, her family said in a statement.

Mourning continued throughout Spain, with Sunday church services being held in remembrance of the dead.

A large funeral mass was planned for Monday afternoon in Santiago de Compostela, and the prime minister and members of the royal family are expected to attend.

Source: Agencies